There are many known processes in which high temperature gases or high temperature fluidized solids are transported through piping systems. For example, in fluid catalytic cracking processes, many of the piping systems employed for transporting gases and fluidized solids from the reactor to the regenerator unit and back are exposed to gases and fluidized solids at temperatures that are in the range of about 500.degree. C. to about 900.degree. C. and have pressures in the range of about 1 to 4 atmospheres. These piping systems are internally insulated with a refractory lining which is either gun-applied or cast in place. In curved pipe sections like elbows, the internal refractory lining layer adds very high stiffness to the curved section, preventing its ovalization and characteristic flexibility, with the result that high unaccounted-for piping loads predispose the piping system to component failures.
Accordingly, the object of the present invention is to provide an internally insulated curved pipe section in which the refractory lining is retained in position, but substantially mechanically decoupled from the curved pipe so that the inherent flexibility of the curved pipe is not significantly affected.